Electrical contact member and method of making the same



May 23, 1950 J. F. sE'rrLE ELECTRICAL CONTACT MEMBER AND OF MAKING THESAME ed Sept. 12, 1946 HEW. a

METHOD Inventor Joseph E Settle,

b5 His Attorney.

Patented May 23, 1950 ELECTRICAL CONTACT MEMBER AND METHOD OF MAKING THESAME Joseph F. Settle, Schenectady, N. Y., asslgnor to General ElectricCompany, a corporation 01' New York Application September 12, 1946,Serial No. 696,551

1 Claim. 1

My invention relates to electrical contact members and to an improvedmethod of making the same.

An object of my invention is to provide an improved electrical member.

Another object of my invention is to provide an improved method ofmaking an electrical contact member.

A further object of my invention is to provide an improved electricalcontact brush member having a carbonaceous material porton and an.arrangement for securing a terminal clip member thereto.

Further objects and advantages of my invention will become apparent andmy invention will be better understood from the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize mv invention will be pointed out with particularity in theclaim annexed to and forming a part of this specification.

In the drawing, Fig. 1 is a sectional side elevational view of a part ofan electrical contact member formed as a brush for electrical rotatingmachinery provided with an embodiment of my invention; and Fig. 2 is asectional side elevational view of a part of the arrangement shown inFig. 1 prior to the final assembly thereof.

Referring to the drawing, I have shown my invention in connection withan electrical contact member formed as a brush adapted to be used tomake a connection between a stationary conductor and a rotatingelectrical device. This contact brush member is shown as having aportion I made of carbonaceous material, such as graphite or a mixtureof graphite and metal powders, or of similar materials, as areconventionally used for such members, and an arrangement is provided forforming a good electrical contact between the contact brush member and astationary terminal through a flexible electrical conductor 2 which iswelded, brazed, or otherwise suitably secured to a terminal clip member3 of any suitable material, such as steel, arranged over an end and incontact with a surface of the carbonaceous material brush portion I. Inorder to provide a secure connection between the terminal clip member 3and the carbonaceous material brush portion I, a passage 4 is preformedin the carbonaceous material brush portion I and a. passage 5 issimilarly preformed in the contact clip member 3. The terminal clipmember is then arranged over an end of the carbonaceous material brushportion with the two passages 4 and 5 substantially in coaxialcorrespondence, as

shown in Fig. 2, and then a two-part rivet is arranged in the passages 4and 5 with stem portions 6 and I of the two parts of the rivet extendingthrough the members I and 3 in the openings 4 and 5 with heads 8 and 9of the rivet part in engagement with the opposite outer side of thecarbonaceous material brush portion and the terminal clip member. Whenthese parts are thus assembled, the two parts of the rivet are adaptedto be welded together by the passage of an electric currenttherethrough, such that the inner adjacent ends l0 and I I of the tworivet parts are welded together by the passage of current therethroughto provide a rigid unitary rivet securing together the terminal memberand the carbonaceous material brush portion I. When the rivet cools, thecontraction thereof assists in providing a still firmer connectionbetween the terminal clip member 3 and the brush member portion I. Thismechanical connection may be further strengthened, and the electricalresistance of the contact between the terminal clip member 3 and thecarbonaceous material brush member portion I may be reduced by providinga bonded coating II of low electrical resistance metal, such as copper,on the surface of the carbonaceous material brush member portion 9adapted to be arranged in contact with the terminal clip member 3 andapplying an adherent coating of an alloying metal, such as tin or zinc,over the surface of the clip member 3 prior to assembly. These twoalloying metals are adapted to be alloyed together to provide a lowresistance bond between the metal of the clip 3 and the carbonaceousmaterial portion I of the brush member by the heat generated by thepassage of current through the two parts of the rivet during the weldingthereof and by the passage of current through the carbonaceous materialbrush portion I and the clip member during this rivet-welding operation.This alloying of the two contact metals is facilitated by theapplication of a non-corrosive flux, such as a mixture of rosin andalcohol, over the surface 01' the alloying metal and particularly overthe surface of the copper coating in order to remove the oxide from theengaging surfaces of the alloying metals and to facilitate thereby thewetting of these adjacent surfaces when the metals become molten. Thisprovides a good electrical and mechanical bond between the terminal'clipmember 3 and the carbonaceous material brush member portion I by thesecure unitary riveted construction of the two-part welded rivet and bythe continuous good electrical contact between the steel clip 3, the tinsurface thereon, the alloy of the tin and copper, the copper surface,and the carbonaceous material I, forming a. goodsteel-totin-to-alioy-to-copper-to-carbonaceous material electricalconductor oi relatively low resistance reinforced by the rivet whichextends therebetween where these or other suitable electricallyconductive members are used in making these parts.

While I have illustrated a particular embodiment of my invention,modifications thereof will occur to those skilled in the art. I desireit to be understood, therefore, that my invention is not to be limitedto the particular arrangement disclosed, and I intend in the appendedclaim to cover all modifications which do not depart from the spirit andscope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

An electrical contact brush having a carbonaceous material portion and ametal terminal clip 20 member adapted to be arranged in contact with asurface of said carbonaceous material portion, said carbonaceousmaterial portion having a coating of copper on the surface thereofadapted to be arranged adjacent said clip member and said 4 metal clipmember having a coating of tin on the face thereoi arranged to beadjacent said carbonaceous material portion, a two-part rivet extendingthrough both said terminal clip member and said carbonaceous materialportion with a head on the outer end of each of said rivet parts andwith the adJacent inner ends of said two rivet parts welded together toform a unitary rivet for securing together said terminal clip member andsaid carbonaceous material brush portion with the heat of said weldforming an alloy between said tin and said copper coatings.

JOSEPH I". SEI'ILE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 661,669 Rohrer Nov, 13, 19001,210,029 Auel Dec. 28, 1916 2,242,014 Martin May 13, 1941 2,436,852Carmichael et al. Mar. 2, 1948

